High energy tube expander



April 1964 G. c. CADWELL HIGH ENERGY TUBE EXPANDER Filed Feb. 17, 1961 HVVENTOR QQCADWELL ATTORNEY mm hm hm mm mm NN mm United States Patent 3,127,923 HIGH ENERGY TUBE EXPANDER Gilbert C. Caldwell, San Diego, Calif., assignor to Rohr Corporation, a corporation of California Filed Feb. 17, 1961, Ser. No. 102,081 Claims. (Cl. 153-79) This invention relates generally to devices for forming metals by explosive means and more particularly to a high energy tube expander in the form of a hand tool having particular utility in the on site forming of tubular join-ts and fittings in high pressure hydraulic lines, or the like, such as may be employed, for example, in the construction of aircraft.

Various devices have heretofore been known or used, and may be suitable for forming tubular joints and fittings at the factory for subsequent on site assembly and brazing together into the various pipe lines, or the like, as aforementioned. This arrangement, however, has not been found to be entirely satisfactory in service for the reason that it is diflicult to preform the tube sections to dimensions and close tolerances such that the preformed and matching tube ends will meet properly during assembly. It frequently is desirable, moreover, to be able to readily repair such joints and fittings in the pipe lines on site and under emergency conditions or to newly form the same in the lines as where modifications are required.

An object of the present invention therefore is to provide a new and improved hand tool for expanding the diameter of thin wall tubing.

Another object is to provide such a tool which expands the tubing by explosive means.

Another object is to provide a high energy tube expander having provision for transfer-ring the energy of an explosive charge uniformly over the inner wall surface of the tube by way of an energy transfer medium.

Another object is to provide an explosive expanding hand tool which is adaptable for use, with normal safety precautions, in an airframe that may be in various stages of assembly or repair.

Still another object is to provide a device for the explosive expanding of tubing which will leave the tubing so formed free of explosive residue and corrosive effects.

Yet another object is to provide an explosive expanding tool for forming joints and fittings in metal tubing without causing internal and external roughness of the surfaces of the tubing due to the explosive charge and/ or the associated tooling.

Another object is to provide an explosive expanding tool of substantially the same order of size of the tub-ing fittings being formed whereby the tool may be operated within available envelope clearances, as measured both axially and circumferentially of the tubing, within the air frame or similar structure having limited access areas.

Still another object -is to provide an explosive expanding tool for the on site forming of joints and fittings in metal pipe lines and having provision for effectively blocking the explosive pressure against entering into equipment that may be connected to the lines being sized or joined.

Still another object is to provide a tube expanding tool for forming joints and fittings in metal pipe lines in which the tool is adapted for ready installation and removal from such lines.

Still another object is to provide a tube expanding tool operable by explosive means and adapted to produce a sized area which is concentric and parallel with that of the tube within which it is formed.

An additional object is to provide an explosive expanding tool having provision for manual and remote control of the explosive charge.

Still other objects, features, and advantages of the present invention are those inherent in or to be implied from the novel combination, construction, and arrangement of par-ts comprising an explosive expanding tool constructed in accordance with the best mode thus far devised for practicing the principles of the present invention, as will become more fully apparent from the following detailed description thereof, reference being had to the accompanying drawings wherein:

FIG. 1 is a sectional view, somewhat enlarged, of an explosive expanding tool of the present invention as viewed from one end thereof;

FIG. 2 is a sectional view of the expanding tool as viewed along the lines 2-2 of FIG. 1 and disclosing the tool in operative relation to a tube being expanded therey;

FIG. 3 is a fragmentary sectional view showing a portion of the tool in the region of forming of the-tube;

FIG. 4 is a view similar to that of FIG. 3 and showing the relationship of the parts and the direction of the explosive forces just after the tube has been formed;

FIG. 5 is a sectional view as viewed along the lines 55 of FIG. 2;

FIG. 6 is a view, somewhat partially broken away, of confronting tube ends which are to be formed into a joint by means of the explosive expanding tool of the present invention;

FIG. 7 is a view similar to that of FIG. 6 and showing the relationship of the confronting tube ends after the same have been expanded;

FIG. 8 is a view showing the joining together of the confronting tube ends disclosed in FIG. 7; and

FIG. 9 is a view disclosing expanded and confronting tube ends which are joined together by a sleeve.

Referring now to the drawings for a more complete description of the invention, and first more particularly to FIGS. 6 thru 9, there is disclosed therein a first pair of tubes 10 and 11, the confronting ends of which are expanded as shown in FIG. 7 and interfittingly joined together in a lap joint as shown in FIG. 8 preparatory to brazing the same together. In FIG. 9, a pair of tubes 12 and 13, each of which has. been expanded in the manner of tube 11 as shown in FIG. 7, are disclosed in abut-ting relation end-to-end and enclosed by a closely interfitting sleeve 14 to thus place the parts in assembled relationship preparatory to brazing the same together.

In a specific example, each of tubes 10 to 13' is a AM-3'50 CRT tube having a nominal outside diameter designated O.'D. of 1.00 inch and a wall thickness t of the order of .042 inch. As commercially available the 0.1). may have a tolerance of the order of .005 inch, that is to say, the outside diameter of the tubing may be .0025 inch more or less than the nominal one inch diameter. For this reason, to properly effect the joints depicted in FIGS. 8 and 9, the tubes 11, 12, and 13 must first be sized, that is, expanded to a predetermined outside diameter depicted O.D.' in FIGS. 7 and 9. This predetermined D. in the specific case assumed may be of the order of 1.010 inch:.0i)3, and the surface expanded to this diameter may extend over a length L which is approximately 60% of the diameter and preferably of the order of .5625 inchiXJdO. In the sleeve joint of FIG. 9, the predetermined 01D. of tubes 12 and 13 will correspond to the predetermined ID. of the sleeve 14 with an allowable tolerance consistent with acceptable brazing practice. In the case of the lap joint depicted in FIG. 8, tube must be expanded such that its internal diameter, designated |I.D. in FIG. 7, in the region of overlap with tube 11, must be such as to conform to the CD. of the tube 11 with an allowable tolerance consistent with acceptable brazing practice. To accomplish this, tube 10 is expanded to an outside diameter designated To meet specific requirements in the assumed example, the region 15 of transition of each of tubes 11, 12 and 13 from the outer surface of the unformed tube to that of the expanded portion thereof would have a radius of the order of inch, and the center line 12 of the expanded tube portions as depicted in FIG. 9 should be concentric and parallel with center line (I; of the unformed tube portions.

A hand tool, operable by explosive means, for forming the tubular joints and fittings depicted in FIGS. 8 and 9 is disclosed in FIGS. 1 thru 5 in operative relation to tube 11, for example, this tool being generally designated 16. In accordance with the aforestated objects of the invention, it is desired to expand the tube ends within the limited access areas and environment of an air frame or like structure that may be in various stages of assembly. In order to meet envelope clearance requirements under such circumstances and conditions, tool 16, or any portion thereof, cannot exceed maximum outside dimensions. Tool 16, however, consistent with these requirements, may vary in over-all size in accordance with the range of diameter of tubes desired to be formed thereby as will more fully apear as the description proceeds. For a one inch tube such as tube 11, for example, tool 16 in conformance with envelope clearance requirements, would not project beyond 1.500 inches of the end of the tube axially, nor would the tool extend radially in any direction from the centerline by more than one and'a half inches. As such, a tool 16 of size compatible for expanding tubes of diameter such as tube 11 is ideally of a size which readily may be held within the hand of the user to thus facilitate both the mounting of the tool on a tube to be expanded and upon manipulating the firing pin during the forming operation, as will more fully apear as the description proceeds.

Tool 16 comprises a circular die which is split along a diameter into two parts 17 and 18 in order to facilitate removal of the tool upon completion of the forming operation. These die parts are aligned axially and circumferentially by means of pins 19 and held in assembled relationship by ring members 20 and 21 which respectively make threaded engagement therewith as at 22 and 23. Ring member 20 and the assembled die parts present complementary cone surfaces indicated at 24 for assuring concentricity of the assembled parts and close fitting of the outer surface of tube 11 and a composite matching surface 25 of the assembled die parts as the ring 20 is threadedly advanced and tightened thereon. Similarly, ring 21 and the assembled die parts present complementary cone surfaces 26 which serve the same purpose.

Die parts 17 and 18 together also provide a circular composite die surface 27 Whose diameter exceeds that of the outer surface of the tube in the amount of tube expansion desired in a particular case. It will be understood that a plurality of die sets such as that comprising die 4 parts 17 and 18 and having die surfaces corresponding to composite die surface 27 but differing in diameter therefrom will be provided and available for use with tool 16 within the limits imposed by the clearance opening 28 provided in ring member 20. Thus, tool 16 will handle tube sizes which will freely pass through the clearance opening 28 in ring member 20 and, in the case of the tube of maximum diameter, the tube gripping surface 25 will be just slightly smaller in diameter than that of the clearance opening 28. The die sets 17, 18 will also range in diameter with respect to the die surfaces 27 in accordance with the degree of expansion required for a tube of given size. Thus, a different die set 17, 18 is re quired to form or expand the end of tube 10 than that employed to expand the confronting end of tube 11. Also, the region 29 in the die surface will conform to the radius of transition required according to the extent of tube expansion to be made in each case.

Two effects are thus desired in the assembly of the split die 17, 18 and its end rings 2% and 21. The first and more important effect is to fully close the composite die surface 27 so that there will be no opening as at 30 where the matching surfaces of the die parts meet along the diameter. This is essential in order to prevent the formation of longitudinal ridges in the expanded tube surface which, if present, would prevent the desired close interfit between the parts and impair the effectiveness of the brazed connection. The second desired effect upon closing of the composite die surface 27 is to establish a close fitting relationship of the composite surface 25 of the split die with the outer surface of the tube. In the event that the diameter of the tube is such as to make the tube somewhat oversize relative to the diameter of the closed surface 25 of the die parts, upon tightening of the rings 20 and 21 thereon, the split die surface 27 will first be closed fully by the ring 21, the closure of these surfaces being unopposed by any confronting surface of the tube. The split die surfaces 25, however, being so opposed by the matching surfaces of the tube may require a compression or necking down of the tube upon further tightening of the ring 2% in order to fully close the gap in the split surface 25. This, of course, is entirely possible within the range of tolerances anticipated in the use of the tool due to the inherent resiliency and initial ovality of the tubes. In the event that the diameter of the tube is somewhat less than that of the closed surfaces 25, such that the tube is not clamped thereby but nevertheless has a closely fitting relationship therewith, a tightly fitting engagement is subsequently produced as the tube, upon expanding the same, initially is expanded outwardly in the region of transition 29 to thus prevent relative movement between the tube and the died parts during the forming operation.

The portion of the tube disposed opposite the composite die face 27 is expanded radially outward into engagement therewith by explosive means disposed within the tubing. The explosive means may be of any type suitable for the purpose and generally comprises a source of explosive energy 31, an energy transfer medium '52, and means generally designated 33 for supporting the energy source and transfer medium in assembled relationship within the tube.

High energy source 31 may be in the form of an extra high power twenty-two caliber blank cartridge of a type commonly employed in stud driving tools, or the like. Cartridges of this type conveniently may be selected with various power levels in accordance with the dimensions of the tubes to be expanded and the extent of expansion re quired in any case.

Energy transfer medium 32 preferably is in the form of a molded neoprene boot or sleeve which fits against the inner-wall of the tube in the region thereof to be expanded and for an additional area extending beyond the transitional region 29. The purpose of the neoprene sleeve or boot is to provide for uniform transfer of the released explosive energy to the innerwall surface of the tube portion to be expanded, to prevent powder impingement on such surface, and to provide a gas trap for preventing gases from blowing by and entering the tube and equipment that may be connected thereto in the pressure line system being assembled, repaired, or otherwise serviced. As aforementioned, the length of the expanded portion of the tube will as a general rule measure about 60% of the tube diameter. For reasons hereinafter more fully to appear, the length of energy transfer sleeve as a general rule will measure about 100% of the tube diameter.

Cartridge holder 33 is generally of cylindrical configuration and is so formed as to receive the energy transfer medium 32 interfittingly therewith and in supported relation thereon. To this end, holder 33 has a main body portion 34 which presents an elongated cylindrical surface 35 upon which the element 32 is sleeved interfittingly therewith. Element 32 is formed cup shaped with a central opening 36 in the base to receive the reduced threaded portion 37 of cartridge holder 33, the transition surface between the holder portions 34 and 37 being rounded as at 38 to facilitate mounting of the sleeve on the holder. Sleeve 35 is held in this position on the holder by means of the cylindrical nut 39 which is threadedly received on the holder portion 37, a felt washer 4'' being interposed between the parts to provide a wiping of the tube inner wall prior to and following the forming operation. Nut 39 provides end wall support for the bottom face of sleeve 32 to prevent expansion of the same longitudinally along the inner-wall of the tube in response to the explosive forces, and tightening of the nut against the sleeve end wall produces a packing gland effect to provide a means of adjusting the outer diameter of the sleeve to bring the same generally into conformance with the inner diameter of the tube in which it is to be inserted.

Holder 33 also has a head or flange portion 41 providing an end face disposed in face adjacency as at 42 with the inner face of ring member 21. Flange 41 provides an inner face against which the end of the tube may be abutted as at 43 to thus provide a stop for limiting the extent of insertion of the sleeved holder into the tube. This surface of the flange is undercut as at 44 to provide a seat for the end of the sleeve, this being desirable, as will subsequently appear, to provide a sealed chamber for enclosing the expanding gases during the forming operation and to prevent leakage of such gases along the outer surface of the tube being formed.

Holder 33 is provided with a central bore 45 for receiving the cartridge 31, and this bore is enlarged at the mouth as at 46 to seat the cartridge flange. Bore 45 is somewhat longer than the cartridge disposed therewithin to provide an explosive chamber 47 for the expansion of the generated gases upon ignition of the cartridge, and this chamber is in communication with the outer cylindrical surface 35 of the holder body portion 34 by means of a plurality of radially directed openings 48 provided therewithin. At least one of these radial openings 48 communicates with the end face of flange 41 by means of a restricted and somewhat narrower longitudinally directed opening 49 which, in turn, is disposed in communication with the surrounding atmosphere by means of an opening 50 provided in end ring 21.

End ring 21 has a central opening 51 and narrowed terminal opening 52 for respectively accommodating the enlarged head and narrowed shank of the firing pin 53 which is slidably disposed within these openings. The other end of bore 51 is enlarged as at 55 so as to match substantially that of opening 46 for accommodating the cartridge flange. Opening 55 is employed to seat a heater ring 56 which may be connected by suitable leads (not shown) for connecting the same into a low voltage circuit to thereby provide for the remote control ignition of the cartridge 31.

The operation of tool 16 should now be apparent from the foregoing description of the various parts thereof, and the following general statement of its manner of operation and use in expanding tube 11 into conformance with the die surfaces 27 and 29 will therefore suflice, it being understood that the same operation generally will be employed in forming other expanded tube portions such as depicted by tube 10.

In preparing tool 16 for expansion of the end portion of tube 11, sleeve 32 and felt washer 40 are first mounted on cartridge holder 33 and secured in position thereon by the nut 39 which is tightened, as required, to expand the diameter of the sleeve. This assembly is then inserted into the end of the tube until the end flange 41 bottoms as at 43 on the end face of the tube. Ring 20 may then be slipped over the end of the tube or, if desired, this ring may be mounted on the tube prior to insertion of the neoprene-sleeved cartridge holder 33 therewithin. The split die parts 17 and 18 are then mounted in position around the tube portion to be expanded and the end rings 20 and 21 screwed thereon to secure the die parts in such position, it being understood, of course, that the cartridge 31 and the firing pin 53 having been disposed within their operative positions in their respective parts 33 and 21 prior to the mounting of the 21 on the split die parts.

In the mechanical or percussion firing of tool 16 as thus assembled on tube 11, the tool may be held in one hand and the firing pin 53 tapped with a moderately heavy object grasped in the other. Upon firing of the cartridge 31, the generated gases expand within the explosive chamber 47 and radially outwardly of the openings 48 as indicated by the arrows in FIG. 4. As also seen in this figure, the force of the expanding gases compresses the neoprene sleeve 32 against the inner-wall of the tubing and lifts the same away from the cylindrical surface 35 of holder 33 to thus momentarily form an annular chamber 57 thereabout. This chamber remains sealed, notwithstanding the displacement of the end portion of the tube into conformance with the die surfaces 27 and 29, because of the interfitting relationship of the sleeve with the recessed end portion of the flange 41 as at 44 and the excess portion of the sleeve which extends in sealed relation to the inner-wall of the tube beyond the transition region 29 therein. From this it follows that the greater the degree of tube expansion, the greater should be the length of the sleeve 32.

Since the annular expansion chamber 57 is thus sealed, the expanding gases are applied fully to the work, except for minor leakage by way of the restricted vents 49 and 50. The gases, moreover, cannot escape into the tube and thence into any equipment connected thereto. As the explosive forces subside, and in the event of generation of forces in excess of those required to form the expanded tube portion, the generated gases escape to the surrounding atmosphere by way of the connected ports 49 and 50.

When the forming operation is complete, the end rings 20 and 21 and split die parts 17 and 18 are removed from tube 11 in the reverse order of their mounting on the tube preparatory to expanding the same. The sleeve mounted cartridge holder is then withdrawn from the tube and the wiping action of the felt washer 40 tends to remove any neoprene particles that may have been separated from the sleeve and deposited upon the inner-wall of the tube. The wiper 40 also serves during the assembly of the tool on the tube and preparatory to expanding the same to clean and dress the inner-wall to facilitate insertion of the sleeved cartridge holder into the tube.

The forming operation as heretofore described is accomplished with a minimum of sound effects and sensed reaction on the part of the operator due to the muflling and cushioning function of the resilient rubber-like energy transfer medium provided by the neoprene sleeve 32.

The tube ends as thus expanded, sized, or otherwise formed on site in the foregoing manner may then be connected together to form the joint or fitting and then brazed to complete the connection, all in accordance with the fulfillment of the aforestated objects of the invention.

This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment of the invention is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. A high energy tube expander of the character disclosed comprising, in combination, means mountable externally of the tube for forming an annular die surface against which an end portion of the tube may be expanded, and explosive means insertable into the tube in force transmitting relation to the inner-wall of said tube portion, said explosive means including an explosive charge, a radially vented holder for said charge, and a resilient rubber-like energy transfer device sleeved on said holder and operatively interposed between said charge and said inner-wall for uniformly applying thereto the explosive forces applied to said energy transfer device through said vented holder and generated by said charge when the same is fired.

2. A hand tool of the character disclosed for expanding metal tubing comprising, in combination, means adapted for assembly about the free end of a tube for forming an annular die surface against which an end portion of the tube is to be expanded and forming an adjacent annular tube engaging surface in interfitting relationship with the external wall of the tube, means including a cartridge, a radially vented cylindrical holder for said cartridge, and a surrounding rubber-like sleeve mounted on said holder and insertable within the tube therewith with adjacent portions of said sleeve disposed opposite said die surface and said adjacent tube engaging surface, said cartridge being operable when fired to generate expanding gases of explosive force, said vented holder being operable to control the pressure and velocity of the expanded gases released therethrough to said sleeve, said sleeve being operable to transfer the energy of said expanding gases to expand said tube portion against said die surface and to form a sealed engagement with the adjacent inner-wall of the tube opposite said tube engaging surface thereby to entrap said gases and prevent the same from entering into the unformed portion of the tube.

3. A hand tool of the character disclosed for expanding metal tubes comprising, in combination, means including a split die adaptable for assembly about the free end of a tube to form an annular die surface against which an end portion of the tube is to be expanded, and explosive means adaptable for assembly and insertion within the tube, said explosive means including a cartridge, a radially vented cartridge holder, and a rubber-like sleeve supported on said holder, said sleeve being disposed in energy transfering relation with respect to said. tube portion and with respect to said cartridge through said vented holder whereby said tube portion is expanded against said die surface when the cartridge is fired.

4. A hand tool of the character disclosed for expanding metal tubes comprising, in combination, means including split dies and retainer rings therefor adaptable for assembly about the free end of a tube for forming an annular die surface against which an end portion of the tube is to be expanded, and high energy transmitting means adaptable for assembly and insertion into the tube, said high energy transmitting means comprising a cartridge holder of cylindrical configuration having a central bore for receiving a cartridge therewithin and having a plurality of radially directed openings extending to the outer cylindrical wall of said holder, a rubber-like member sleeved on said outer cylindrical wall in closing relation with respect to said radially directed openings, said sleeve being disposed within the tube in energy transmitting relation with respect to said tube portion to be expanded, and means carried by one of said rings for firing a cartridge seated within said central bore.

5. A hand tool of the character disclosed for expanding metal tubes comprising, in combination, means adapted for assembly about the free end of a tube for forming an annular die surface against which an end portion of the tube is to be expanded, high energy transfer means adapted for assembly and insertion into the tube and including a radially vented cartridge holder and a resilient energy transfer device sleeved on said holder for entrapping and applying the resulting high energy explosive forces transferred through said vented holder to said sleeved device and from the sleeved device to said tube portion when a cartridge is fired in said holder, and means carried by said die surface forming means for firing a cartridge inserted into said holder.

6. A hand tool of the character disclosed for expanding metal tubes comprising, in combination, die means adaptable for assembly on the free end of a tube, said die means including a splie die forming a composite annular die surface about an end portion of the tube to be expanded when the split die is assembled on the tube, a first ring member slidable over the end of the tube, a second ring member of cup-shaped configuration and mountable on the end of the tube, said ring members having said split die interposed axially therebetween and threadably engageable respectively with the ends thereof, said split die and each of said ring members having complementary cone surfaces for concentrically aligning said die surface with the axis of said tube as the ring members are threadedly tightened on the split die, a cylindrically shaped cartridge holder having a cartridge chamber and openings radially directed from said chamber to the cylindrical outer surface of the holder, said holder being insertable within the tube and having an outer rubber-like sleeve positioned on the cylindrical surface of the holder in energy receiving relation to a cartridge inserted in said chamber and fired therewithin, said sleeve in position on said holder being adapted to be positioned in energy transferring sealing relation with respect to said tube portion to be expanded, and means carried by said second ring member for firing said cartridge inserted within said cartridge holder.

7. A hand tool as in claim 6, said firing means com prising a firing pin slidably supported for movement axially of said second ring member, said pin having a portion extending externally of said second ring member for actuation of the pin and an inner portion engageable with said cartridge for percussion firing of the same.

8. A hand tool as in claim 6, said firing means comprising a heater element adaptable for ignition of said cartridge by electrical circuit means.

9. A hand tool of the character disclosed for expanding metal tubes comprising, in combination, die means adaptable for assembly about the free end of a tube and including a split die and a pair of ring members respectively engageable threadedly with the ends of the split die when assembled on the tube, said split die having a composite annular surface when so assembled and against which an end portion of the tube is to be formed, high energy transfer means adapted for assembly and insertion within the tube and including a cartridge holder of cylindrical configuration, said holder having a flanged head at one end and a main body portion, said flanged head having an inner end face engageable with the end of the tube to limit insertion of the energy transfer assembly into the tube, said inner end face having an annular recess, a rubber-like member sleeved on said main body portion of the holder and having one end thereof seated within said annular groove of the head flange, means on said main body portion of the holder for seating and sealing the other end of said rubber-like member thereto, said body portion having a central bore for receiving a cartridge therewithin and a plurality of openings extending radially from said central bore to the cylindrical wall in engagement with said rubber-like member, and means carried by one of said rings for firing a cartridge inserted in said holder.

10. A hand tool as in claim 9 and further comprising means for exhausting to the atmosphere gases generated within said holder upon firing of a cartridge therewithin.

References Cited in the file of this patent UNITED STATES PATENTS Middler Apr. 21, 1936 Temple Mar. 10, 1942 Drexelius May 29, 1962 Callahan July 24, 1962 FOREIGN PATENTS Great Britain Feb. 27, 1942 Great Britain Jan. 23, 1957 

1. A HIGH ENERGY TUBE EXPANDER OF THE CHARACTER DISCLOSED COMPRISING, IN COMBINATION, MEANS MOUNTABLE EXTERNALLY OF THE TUBE FOR FORMING AN ANNULAR DIE SURFACE AGAINST WHICH AN END PORTION OF THE TUBE MAY BE EXPANDED, AND EXPLOSIVE MEANS INSERTABLE INTO THE TUBE IN FORCE TRANSMITTING RELATION TO THE INNER-WALL OF SAID TUBE PORTION, SAID EXPLOSIVE MEANS INCLUDING AN EXPLOSIVE CHARGE, A RADIALLY VENTED HOLDER FOR SAID CHARGE, AND A RESILIENT RUBBER-LIKE ENERGY TRANSFER DEVICE SLEEVED ON SAID HOLDER AND OPERATIVELY INTERPOSED BETWEEN SAID CHARGE AND SAID INNER-WALL FOR UNIFORMLY APPLYING THERETO THE EXPLOSIVE FORCES APPLIED TO SAID ENERGY TRANSFER DEVICE THROUGH SAID VENTED HOLDER AND GENERATED BY SAID CHARGE WHEN THE SAME IS FIRED. 